Synthesis of (S)-2-aminonon-8-enoic acid has been reported in the literature. Faucher, et al., reported a six step synthetic sequence for (S)-2-aminonon-8-enoic acid, which involves catalytic hydrogenation of an enamine substrate utilizing a DUPHOS ligand system as the key step for introduction of α-amino acid chirality (Org. Lett. 2004, 6, 2901-2904). Subsequently, Wang, et al., reported an enzymatic approach for the preparation of (S)-2-aminonon-8-enoic acid using acylase for the selective kinetic hydrolysis of a racemic acetamide substrate, with a theoretical step yield of 50%, in a six-step sequence (Org. Process Res. Dev. 2007, 11, 60-63). In 2008, an alternate approach involving a whole-cell catalytic system was disclosed for preparation of enantiomerically enriched (S)-2-aminonon-8-enoic acid from the corresponding hydantoin substrate (WO 2008/067981 A2). Subsequently, a different approach was reported (WO 2010/050516 A1; WO 2008/067981 A2) for (S)-2-aminonon-8-enoic acid, which was also based on selective kinetic hydrolysis of a racemic succinyl amide substrate using an L-succinylase enzyme (amidase), with a theoretical 50% step yield.
Previously disclosed methods are neither efficient nor best suited for the large-scale preparation of (S)-2-aminonon-8-enoic acid, as some of them involve multiple steps, with individual steps within a sequence possessing the limitation of a maximum 50% theoretical step yield. Thus, there is a need in the art for an improved process for preparing (S)-2-aminonon-8-enoic acid.